United States Patent 9,456,993: Claim Scope, Amphetamine Patch Protection, and Patent Landscape
U.S. Patent No. 9,456,993 protects a specific amphetamine transdermal patch architecture rather than amphetamine delivery in the abstract. Its independent composition claim requires four core elements: an amphetamine-containing polymer matrix, a flexible finite topical system, a multilayer backing, and a polyurethane adhesive positioned between polyurethane and polyester films. Dependent claims narrow the protection to d-amphetamine free base, defined acrylic matrices, loading levels, dimensions, release performance, stability, and therapeutic uses.[1]
The patent is most relevant to transdermal d-amphetamine products such as Xelstrym. Its strongest infringement position is against a patch that uses the claimed polyurethane/polyester backing construction together with the specified amphetamine acrylic matrix. A competing product can reduce literal-infringement risk by changing the backing materials, adhesive chemistry, matrix composition, drug loading, or product architecture.
What does U.S. Patent 9,456,993 protect?
Claim 1 protects a combination of formulation and device components. Each limitation must be present for literal infringement.
| Claim element |
Required limitation |
| Dosage form |
Flexible finite system for topical application |
| Active ingredient |
Amphetamine, pharmaceutically acceptable salt, or prodrug |
| Drug reservoir |
Polymer matrix containing the active |
| Backing layer |
Polyurethane film layer plus polyester film layer |
| Interlayer adhesive |
Polyurethane adhesive between the two backing films |
| Matrix-facing layer |
Polyurethane film layer is adjacent to the polymer matrix |
| Adhesive chemistry |
Isocyanate-terminated polyether urethane or isocyanate-terminated polyester urethane |
| Adhesive condition |
May be cured or part of a two-component adhesive |
The claim does not require a particular amphetamine dose, therapeutic indication, matrix polymer, patch size, release rate, or commercial brand. Those requirements appear in dependent claims or claim 26.
The patent therefore has a layered protection strategy. Claim 1 captures the physical product architecture. Claims 2 through 25 progressively narrow the materials and performance characteristics. Claim 26 separately covers specified therapeutic uses.
How strong is the independent claim?
Claim 1 has meaningful structural specificity but a relatively narrow combination scope.
The principal strength is the required relationship among the layers. The claim does not merely recite a polyurethane backing or an amphetamine patch. It requires:
- A polyurethane film adjacent to the drug matrix.
- A polyester film behind that polyurethane film.
- A polyurethane adhesive between the two films.
- A specified class of isocyanate-terminated polyurethane adhesives.
A patch using a polyester film directly against the matrix, a single-layer backing, a non-polyurethane interlayer, or a polyurethane adhesive outside the claimed position may avoid literal infringement.
The principal limitation is that the claim depends on a specific backing construction. A formulation developer can potentially preserve the amphetamine matrix while designing around the backing claim. Conversely, a generic using the same commercial patch construction may face a substantial product-by-process comparison even if its matrix composition differs.
The claim also uses open-ended "comprising" language. Additional layers, excipients, release liners, curing agents, or adhesive components generally do not remove a product from the claim if all required elements remain present.[1]
What do claims 2 through 7 add to the backing layer?
Claims 2 through 7 create a focused material sub-estate around the backing.
| Claim |
Additional limitation |
| 2 |
Polyether aromatic polyurethane polymer |
| 3 |
Polyurethane film thickness of about 1.5 mils |
| 4 |
Polyester film thickness of about 0.4 to 0.6 mils |
| 5 |
Isocyanate-terminated polyether or polyester urethane, optionally cured |
| 6 |
Isocyanate-terminated polyether urethane, optionally cured with a curing agent |
| 7 |
Isocyanate-terminated polyester urethane, optionally cured with a curing agent |
| 27 |
Adhesive cured by moisture or a curing agent |
| 28 |
Adhesive contains a coreactant |
| 29 |
Adhesive thickness of about 0.1 to 1.0 mils |
Claims 6 and 7 divide the adhesive limitation into polyether and polyester urethane alternatives. Claims 27 through 29 broaden the practical manufacturing detail by addressing curing mechanisms, coreactants, and adhesive thickness.
The thickness limitations are narrower than claim 1 and may be difficult to establish without formulation-development records, supplier specifications, microscopy, or destructive product testing. The material identity and layer order are more likely to be central to a paragraph IV certification or infringement investigation.
What amphetamine formulations are covered?
Claims 8 through 15 define the principal matrix formulation scope.
Active ingredient
Claim 8 narrows the active to d-amphetamine free base. This is commercially important because the approved transdermal product Xelstrym contains d-amphetamine.[2]
Claim 1 remains broader because it covers amphetamine salts and prodrugs. A product using a different amphetamine salt could still fall within claim 1 if it uses the required patch construction.
Acrylic polymer matrix
Claims 9 and 10 require at least one acrylic polymer and, more narrowly, at least one non-acid-functional acrylic polymer.
Claim 11 identifies a non-acid-functional acrylic system containing:
- Methyl acrylate;
- 2-ethylhexyl acrylate; and
- Optionally, methyl methacrylate.
Claim 12 identifies another system containing:
- Methyl acrylate;
- 2-ethylhexyl acrylate;
- Butyl acrylate;
- Amide-group-containing monomers; and
- Optionally, methyl methacrylate.
Claim 14 combines two acrylic polymers:
- A first polymer containing 50% methyl acrylate and 50% 2-ethylhexyl acrylate by polymer weight; and
- A second polymer containing methyl acrylate, 2-ethylhexyl acrylate, butyl acrylate, and amide-group-containing monomers.
Claim 15 narrows the dry matrix to:
| Matrix component |
Weight percentage |
| First non-acid-functional acrylic polymer |
67.5% |
| Second non-acid-functional acrylic polymer |
17.5% |
| Amphetamine |
15.0% |
This formulation specificity creates a narrower but potentially stronger product-read-through position where the commercial patch uses the claimed composition.
What drug loading, patch size, and release characteristics are claimed?
Claims 13 and 16 through 23 address quantitative product characteristics.
| Claim |
Quantitative limitation |
| 13 |
About 10% to 20% amphetamine by polymer-matrix weight |
| 15 |
15% amphetamine in the defined acrylic matrix |
| 16 |
Matrix coat weight of about 6 to 8 mg/cm² |
| 17 |
About 1 mg/cm² amphetamine |
| 18 |
Patch size of about 2 to 60 cm² |
| 20 |
Amphetamine delivery over about 8 to 10 hours |
| 21 |
Onset period of about 30 to 90 minutes |
| 22 |
Therapeutic effect for at least about 12 hours when removed after about 9 hours |
| 23 |
Drug depletion of about 85% to 93% after about 8 to 10 hours |
These limitations are commercially aligned with a patch applied before therapeutic effect is needed and removed after a defined wear period. Xelstrym labeling directs application two hours before an effect is needed and removal within nine hours.[2]
The performance claims may be difficult to use as standalone competitive barriers unless the accused patch satisfies all preceding composition limitations. They are dependent claims, so a product must first meet claim 1 and the relevant intervening limitations. Release testing, in vitro permeation testing, pharmacokinetic studies, and residual-drug analysis would be relevant evidence.
What stability protection does U.S. Patent 9,456,993 provide?
Claims 24 and 25 protect product stability against degradant formation.
Claim 24 requires that the composition be stable against formation of degradants. Claim 25 specifies no more than about 1.0% w/w degradants after storage at 40°C for 3.5 months.
This protection can reach beyond the initial formulation recipe. A competing product may use similar matrix polymers but generate a different impurity profile. Conversely, if the same matrix and backing produce the same stability result, claim 25 may create an evidentiary issue in an infringement case.
Stability claims are usually dependent product claims. They are strongest when the claimed threshold is reproducible and the analytical method is defined in the patent specification or regulatory records. The claim text supplied does not identify the degradant assay, acceptance criteria for individual impurities, or exact storage humidity conditions.[1]
Does claim 26 cover ADHD treatment?
Yes. Claim 26 covers a method of:
- Stimulating the central nervous system;
- Treating attention deficit disorder;
- Treating attention deficit hyperactivity disorder; or
- Treating narcolepsy,
by administering a composition according to claim 1.
The method claim is limited by incorporation of every limitation of claim 1. It does not independently cover oral amphetamine, an injectable product, or a transdermal product with a different backing construction.
FDA approved Xelstrym, a d-amphetamine transdermal system, for the treatment of ADHD in patients six years of age and older.[2] The approved product is therefore commercially aligned with the ADHD portion of claim 26, subject to the separate question of whether the marketed product satisfies the structural limitations of claim 1.
What is the Orange Book relevance of U.S. Patent 9,456,993?
The Orange Book records patents and regulatory exclusivity associated with approved drug products. For a transdermal amphetamine product, the relevant inquiry is whether the patent is listed against the approved reference product and whether the approved product's labeling corresponds to a claimed method of use or product characteristic.[3]
A patent listing does not establish infringement or validity. It affects the generic approval pathway. If an ANDA applicant identifies a listed patent and files a paragraph IV certification, the patent holder may bring suit under the Hatch-Waxman Act. A timely suit can trigger a statutory stay of FDA approval for up to 30 months, subject to statutory exceptions and court developments.[4]
The claim set indicates two possible listing theories:
- Product claims covering the transdermal system and its backing/matrix architecture.
- Method-of-use claims covering ADHD, ADD, narcolepsy, or central nervous system stimulation.
Whether U.S. Patent 9,456,993 is currently listed for a particular reference product, whether it has a pediatric or regulatory exclusivity interaction, and whether any paragraph IV challenge has been filed are live database questions governed by the FDA Orange Book and USPTO Patent Center records.[3,5] Those issues cannot be determined from the claim text alone.
When does U.S. Patent 9,456,993 lose exclusivity?
The patent term cannot be calculated from the patent number or claim language alone. U.S. patent expiration depends principally on:
- The earliest effective nonprovisional filing date;
- Any priority claims;
- Patent term adjustment;
- Patent term extension;
- Terminal disclaimers; and
- The prosecution history.
The relevant statutory framework generally provides a term of 20 years from the earliest effective U.S. nonprovisional filing date, subject to adjustments and extensions.[6] The grant date, October 4, 2016, does not by itself establish the expiration date.
For commercial diligence, the controlling record is the USPTO Patent Center continuity and term-adjustment data, supplemented by any FDA patent-term-extension record. A patent expiration date should not be inferred solely from the 2016 grant date.
Which products and competitors create the main risk?
Xelstrym
Xelstrym is the most directly relevant commercial product because it is a d-amphetamine transdermal system indicated for ADHD.[2] Its labeled use, wear period, and dose strengths are consistent with several dependent claims, including claims 8, 20, 21, and 22.
Generic d-amphetamine patches
A future generic applicant would likely evaluate:
- The backing-film supplier and film composition;
- Adhesive chemistry and cure system;
- Layer thickness;
- Acrylic polymer composition;
- Amphetamine loading;
- Patch coat weight;
- Drug depletion;
- Degradant profile; and
- The asserted method of use.
A generic could pursue a paragraph IV certification against listed patents or a section viii statement for carved-out method claims, depending on the scope and status of the Orange Book listing.[4]
Other stimulant delivery systems
Oral methylphenidate, oral amphetamine salts, lisdexamfetamine, and non-amphetamine transdermal stimulants are not direct product substitutes for purposes of claim 1 because they do not use the claimed amphetamine patch architecture. They remain commercial competitors but generally present low literal-infringement risk under this patent.
Is there biosimilar risk?
No conventional biosimilar pathway applies. Amphetamine is a small-molecule active ingredient, and an equivalent transdermal product would ordinarily proceed through the ANDA framework under section 505(j), not the biosimilar pathway under section 351(k).[4,7]
The principal regulatory risks are therefore generic-equivalence, bioequivalence, adhesion, adhesion-related safety, residual drug, dose delivery, abuse-deterrence considerations if applicable, and patent certification issues. Biosimilar interchangeability and biologic-manufacturing questions are not relevant to this patent.
What manufacturing and IP barriers matter most?
The highest-value manufacturing barriers are concentrated in the backing and adhesive system:
- Maintaining polyurethane-film compatibility with the acrylic matrix;
- Preventing migration or interaction between amphetamine and adhesive components;
- Controlling adhesive cure and residual isocyanate chemistry;
- Achieving the claimed film thicknesses;
- Maintaining adhesion over the intended wear period;
- Controlling degradants at accelerated temperature; and
- Producing consistent drug loading across the active surface area.
The patent's practical barrier is strongest when the same construction is needed to achieve the marketed product's adhesion, stability, and release profile. A design-around using a different backing polymer or adhesive may avoid the claims but require new formulation development, manufacturing validation, stability work, and FDA bridging data.
What patent litigation and settlement exposure should be assessed?
The supplied claim set does not establish any litigation, paragraph IV filing, or settlement agreement. Those matters require review of PACER, FDA Orange Book records, FDA litigation notifications, and USPTO prosecution records.
For a generic-entry assessment, the relevant questions are:
| Issue |
Commercial consequence |
| Listed product patent |
May require paragraph IV certification |
| Timely infringement suit |
Potential 30-month approval stay |
| Method-of-use listing |
Possible section viii carve-out, depending on claim scope |
| Product-architecture claim |
More difficult to carve out if the generic product itself practices the claim |
| Unexpired patent with no terminal disclaimer |
Potential launch delay or litigation exposure |
| Settlement agreement |
May establish an agreed entry date or licensing terms |
| Invalidity or noninfringement finding |
Could remove or narrow the barrier |
How does this patent compare with a broader amphetamine patent?
U.S. Patent 9,456,993 is narrower than a patent claiming any transdermal amphetamine composition. Its value lies in the required combination of:
- Amphetamine;
- Acrylic polymer matrix;
- Flexible finite patch;
- Polyurethane film;
- Polyester film;
- Interposed polyurethane adhesive; and
- Specified adhesive chemistry.
A broader formulation patent could cover a wider range of matrices or delivery systems but may face greater prior-art exposure. This patent's structural detail can improve validity prospects against broad prior art, while reducing coverage of alternative patch designs.
Key Takeaways
- U.S. Patent 9,456,993 is a combination patent for an amphetamine transdermal patch.
- Claim 1 requires a polyurethane film/polyester film backing with a specified polyurethane adhesive between the films.
- The polyurethane layer must be adjacent to the amphetamine-containing polymer matrix.
- Dependent claims narrow the invention to d-amphetamine, acrylic polymers, specific monomer systems, loading levels, dimensions, release behavior, and stability.
- Claim 26 covers treatment of ADHD, ADD, narcolepsy, and central nervous system stimulation using the claimed patch.
- Xelstrym is the most commercially relevant product because it is an FDA-approved d-amphetamine transdermal system for ADHD.[2]
- Generic risk depends primarily on whether the generic patch copies the backing architecture and whether the patent is listed and unexpired.
- Biosimilar risk is not relevant because amphetamine is a small molecule.
- Patent expiration, Orange Book listing, paragraph IV activity, litigation, and settlement status require live review of the USPTO and FDA records.
Frequently Asked Questions
Can a patch avoid U.S. Patent 9,456,993 by using a non-polyurethane adhesive?
Potentially. Claim 1 requires a polyurethane adhesive selected from specified isocyanate-terminated polyether or polyester urethanes. A different adhesive chemistry may avoid literal infringement, subject to the doctrine of equivalents and the complete claim construction.
Does the patent cover oral Adderall or Vyvanse?
No. The claims require a flexible finite system for topical application with the claimed backing and matrix architecture. Oral amphetamine products do not meet those limitations.
Does using amphetamine sulfate instead of d-amphetamine free base avoid the patent?
Not necessarily. Claim 8 is limited to d-amphetamine free base, but claim 1 covers amphetamine and pharmaceutically acceptable salts or prodrugs. An amphetamine-salt patch could still implicate claim 1 if the structural limitations are met.
Can a generic omit the ADHD indication to avoid claim 26?
Possibly, if the relevant patent is listed only for the method of use and the generic labeling can lawfully omit the patented indication. That strategy does not avoid product claims covering the patch itself.
What testing would be needed to evaluate infringement?
The main evidence would include layer microscopy, Fourier-transform infrared or other polymer identification, adhesive formulation records, film thickness measurements, matrix composition analysis, amphetamine loading, coat weight, release testing, and accelerated-stability impurity data.
References
- U.S. Patent No. 9,456,993, claims 1-29.
- U.S. Food and Drug Administration. (2022). XELSTRYM (dextroamphetamine) transdermal system prescribing information.
- U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
- U.S. Food and Drug Administration. (2015). ANDA submissions: Amendments and supplements; final rule.
- United States Patent and Trademark Office. (2024). Patent Center.
- 35 U.S.C. §§ 154, 156.
- Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j); Public Health Service Act, 42 U.S.C. § 262(k).
